# 定义两个字符串
string_one = "bread and "
string_two = 'milk'
print(string_one + string_two)      # 俩字符串拼接
print('-' * 20)                     # 输出一条直线
print(string_one[0])                # 索引字符串中的字符
print(string_two[0:4])              # 截取字符串